In a semiconductor production plant, there is a plurality of processing apparatuses to perform various processes for workpieces. In recent years, semiconductor production plants have been expended in scale, and there has been a demand to reduce energy consumption.
For example, there is discloses a technique for achieving energy saving by automatically transitioning from a normal state to an idle state, if standby time of a processing apparatus exceeds a predetermined time. In addition, there is a technique for switching to an operation mode in consideration of recovery time required for a processing apparatus to switch to the operation mode. In this manner, there are various techniques for reducing energy consumption of the processing apparatus.
Workpieces are transferred to each processing apparatus by a transfer apparatus. Some big semiconductor production plants may have thousands of transfer apparatuses. This may require energy consumption of the transfer apparatuses to be limited as well as the processing apparatuses.
There is also a technique for selecting a proper transfer carriage based on predicting when articles can be loaded on a transfer carriage and arrival time of the transfer carriage to a station.
In general, when the workpiece is carried into a processing apparatus, the transfer apparatus circulates on a transfer path and calculates an unloading timing of the workpiece to the processing apparatus until the processing apparatus enters a state where the workpiece can be mounted. While the transfer apparatus is circulating, the transfer apparatus consumes wasteful energy, which has no contribution to the manufacture of semiconductor products.
In addition, there is a technique which selects only a proper transfer carriage, without considering selection of a proper processing apparatus from a plurality of processing apparatuses. This may result in extension of a transfer path, and hence wasteful energy consumption for a transfer.